Years ago, computer rooms used Halon gas to extinguish fires in computer rooms by depriving the room swiftly of oxygen, killing the fire, but keeping expensive equipment safe (vs. sprinkler systems). Halon production was stopped in the 1990's because of its ozone-killing effect, but I think it had another disadvantage: it would kill humans in the computer room as well as the fire. Internet research not clear on that. My novel puts people in a present-day but older server farm near St. Petersburg, Russia, that has gone to seed. It's protected either by older Halon or CO2, so if a fire were to be started, the outer doors would slam shut, and anyone inside would have how long to get out?
In most server rooms which I have designed have:
- Lights next to floor, like in plane, leading to exit
- Lights on exit
- Security buttons (with nearby flash lights) on walls/racks - when pressed, a 10 second delay occurs for closing door and gas release.
- Sound system which announces an evacuation order and countdown untill gas release.
- Emergency door opening system even if gas was already released
These systems are battery powered or strictly mechanical and duplicated.
Time to get out - depends. some have 10-30 seconds. Some have instant if security flag is marked as empty (no one used security door to enter Server room or all cards signed as leaved). One have non oxygen atmosphere at all time (including normal operation - any modification there was pain because of special suits with air tanks).
There are 4 server rooms near St. Petersburg (50km range) with gas extinguish system wich I know about. 3 have 10-30 seconds delay, lights only on exit, no buttons to delay but they are so smal that can evacuate in 2-3 seconds, one have security related; instant if empty (including move detection system) 60 seconds delay if anyone present inside with sparse delay buttons, moving lights on floor and celling to exit. All have emergency button to open door even if gas was released.
They will die from the fire.
Don't forget the reason the doors close - the fire. It is in there with them. If the protection system is broken and fire is too big for them to put out with whatever they have on hand, the room will fill with smoke within a minute. They could get a little more time by lying on the floor but just a little.
You can have your characters have an exchange while lying on the floor. One of them notes that dying from Halon would be better, because it would not stink as bad as the smoke.